Origin and Propagation of an Incorrect Chemical Degradation Pathway in the Literature: cis-1,2-Dichloroethylene as a Daughter Product of 1,1,1-Trichloroethane

Abstract

The correct understanding of contaminant degradation pathways is essential for well-informed decision processes regarding site assessment, monitored natural attenuation, and environmental liability proceedings. Over a 20-year period, and including at least one recent regulatory publication, it has been erroneously reported that cis-1,2-dichloroethylene (cis-DCE) is the daughter product of 1,1,1-trichloroethane (1,1,1-TCA). To clarify the degradation pathways of 1,1,1-TCA, and to corroborate that cis-DCE is not a degradation product of 1,1,1-TCA as suggested and propagated by some sources, we conducted a detailed review of the available literature and mapped out a citation history of 27 publications and reports which contain both the correct and incorrect degradation pathways. Other than the sources containing the erroneous degradation pathways, the reviewed literature shows that cis-DCE is not a proven transformation product of 1,1,1-TCA.

Keywords:

• 1,1,1-trichloroethane (1,1,1-TCA)
• cis-1,2-dichloroethylene (cis-DCE)
• transformation pathways
• degradation products
• monitored natural attenuation

Acknowledgement

The authors would like to acknowledge the contributions of John Connor of GSI Environmental and Ron Lewis of Marshall & Lewis LLP. The authors would also like to thank the reviewers for their helpful comments.